Temperature variations extracted from ring widths of firs growing in the humid environment of the mid-Qinling Mountains

In comparison to trees that grow in arid areas, those growing in humid areas usually have ambiguous climatic information recorded in their ring widths. In this study, ring width samples of Abies chensiensis, collected from the headwaters of the Jialing River in the mid-Qinling Mountains, were used to investigate if temperature signals from the ring widths of trees in humid areas can be extracted. By employing data processing techniques such as first-order difference processing of all series, correlation analysis using pentad meteorological data, and outlier elimination, we found that the inter-annual variations in the average minimum temperature of the pentad 10–23 (MT_10–23) was the limiting factor for radial growth. In humid areas, the moisture content of the air and soil may weaken (or impede) the limiting effect of temperature on trees, and correlation results between chronology and temperature cannot meet the requirements of climate reconstruction, mainly due to the inconsistency of their low-frequency variations. Therefore, accurate extraction of high-frequency temperature signals may be the key to climate reconstruction from tree-ring widths in humid areas.